In recent years, as a measure against reduction in power feed capacity due to a disaster, efforts for reducing energy consumption are considered to be important, and distributed-type power supply systems represented by a photovoltaic generation system are spreading. Under such circumstances, a distributed-type power supply system having a power conversion device for converting power (e.g., storage battery power in an electric vehicle) stored during the night or the like from DC power to AC power is spreading. In this system, it is necessary to confirm soundness before interconnection with a DC power supply.
A power conversion device is disclosed in which, before a storage battery in an electric vehicle and a power conversion device are interconnected, a capacitor provided to power conversion means is charged by a step-up unit, the voltage is further stepped up using an AC/DC converter, and insulation diagnosis voltage is applied between the electric vehicle and the power conversion device, thereby confirming soundness (for example, Patent Document 1).